A device of the type described above is known from DE 34 20 157 C1, which has a sieve grate shaped like a cylinder jacket set obliquely with its axis in a channel while the grate is hydraulically open on the inlet side and largely hydraulically closed on the outlet side. The sieve grate has a slot-hole perforation that forms a deposit area in the inner side, while the liquid passes through the slot, remaining in the channel. The sieve grate is rotationally driven with a screw conveyor that starts in a collecting funnel, which is coaxially fixed in place and seated in the channel area. Above the collecting funnel, on the outside of the grate, a stationary arranged separating device shaped like a brush roller or a spray water bar has been provided to separate from the exterior the floating material that is on the inner side of the sieve grate. The floating material finally falls into the collecting funnel on which the screw conveyor begins and is transported away to a discharge station located away from the liquid.
Similar working filters are used in the shape of so-called drum filters, driven mostly around a horizontal rotating axis. They find an application in the most varied industrial sectors, such as in sewage water treatment, paper manufacturing or also in the food industry.
Whereas the mentioned filters are ideally suited for removing larger and heavier impurities from a fluid, when there are very fine or slight impurities there are frequently problems during the removal of the floating substances from the sieve devices, as they cannot be captured well enough by the discharge device or they refloat in this area, thus making their discharge a lot harder.
It is therefore a task of this invention to suggest a device and a process for removing floating substances of the most varied size and mass from a liquid but nonetheless retain the advantages of conventional rotation filters.